Environmentally friendly fuel gas within a refillable and non-corrosive gas cylinder

ABSTRACT

An article is provided that can be used as a heating source for various applications. The article includes an environmentally friendly gaseous fuel mixture within a gas cylinder that is both non-corrosive and refillable. More specifically, the gaseous fuel mixture contains hydrogen and methane. Methods of using the article as a heating source are also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 13/462,444, filed May 2, 2012 (now U.S. Pat. No. 8,733,543),which claims the benefit of U.S. Provisional Application Ser. No.61/485,225, filed 12 May 2011, May 12, 2011. The disclosures of theprior applications are considered part of (and are incorporated byreference in) the disclosure of this application.

TECHNICAL FIELD

The present invention relates to articles that can be used as a heatingsource and methods of heating. The articles include a non-corrosive,refillable gas cylinder containing a gaseous fuel mixture.

BACKGROUND OF THE INVENTION

Gas cylinders containing a compressed fuel gas are commerciallyavailable in a variety of sizes that can be used as a source of heat(i.e., heating source). Gas cylinders that are of a portable size areoften not reusable (i.e., refillable). After the compressed fuel gas hasbeen used as a heating source, the gas cylinders can present anenvironmental hazard if they are not disposed of properly. Morespecifically, the gas cylinders often contain some residual fuel (i.e.,residual compressed gas) inside after normal use. If the gas cylindersundergo corrosion, the residual fuel can be released. This release canpose both an environmental problem and a potential fire or explosionhazard.

Fuel gases are often used to heat metal in various metallurgicalapplications. One commonly used fuel gas for fusion welding and brazingis acetylene. Acetylene has a number of drawbacks as a fuel gas,particularly for use in portable gas cylinders. It is explosive if thepressure exceeds about 15 pounds per square inch (psi). For this reason,acetylene is usually dissolved in acetone or another organic solvent toimprove its stability. Further, various porous filler materials aretypically placed in gas cylinders used with acetylene to further improvestability. The addition of these porous materials can adversely impactthe total weight of the gas cylinder containing acetylene. Further,addition of these porous materials can create a disposal problem becausethe used porous materials may be considered a hazardous waste.

SUMMARY OF THE INVENTION

An article is provided that can be used, when combined with anoxygen-containing gas, as a heating source for various applications,particularly for non-welding metallurgical applications. The articleincludes a gas cylinder containing an environmentally friendly gaseousfuel mixture. The gas cylinders are both non-corrosive and refillable.More specifically, the gaseous fuel mixture contains hydrogen andmethane. Methods of using the article as a heating source are alsoprovided.

In a first aspect an article is provided that includes a gaseous fuelmixture and a refillable gas cylinder. The gaseous fuel mixturecomprises (a) hydrogen in an amount in a range of 30 to 95 volumepercent based on a total volume of the gaseous fuel mixture and (b)methane in an amount in a range of 5 to 70 weight percent based on thetotal volume of the gaseous fuel mixture. The gas cylinder has (a) anon-corrosive container and (b) a valve that is connected to thenon-corrosive container and that is suitable for use with ahydrogen-containing gas. The gaseous fuel mixture is positioned withinthe non-corrosive container of the gas cylinder.

In a second aspect, a heating method is provided that can beenvironmentally friendly. The method includes providing a refillable gascylinder having a non-corrosive container and a valve that is connectedto the non-corrosive container and that is suitable for use with ahydrogen-containing gas. The method further includes at least partiallyfilling the non-corrosive container of the gas cylinder with a gaseousfuel mixture that contains both hydrogen and methane. Hydrogen ispresent in the gaseous fuel mixture in an amount in a range of 30 to 95volume percent based on a total volume of the gaseous fuel mixture.Methane is present in the gaseous fuel mixture in an amount in a rangeof 5 to 70 volume percent based on the total volume of the gaseous fuelmixture. The method still further includes supplying a heating source,wherein supplying includes discharging at least a portion of the gaseousfuel mixture from the non-corrosive container through the valve andcombining the gaseous fuel mixture with an oxygen-containing gas. Afterdischarging, the method yet further includes adding additional gaseousfuel mixture to the non-corrosive container through the valve.

In a third aspect, an article is provided that includes a gaseous fuelmixture and a refillable gas cylinder. The gaseous fuel mixturecomprises (a) hydrogen in an amount in a range of 70 to 95 volumepercent based on a total volume of the gaseous fuel mixture, (b) methanein an amount in a range of 5 to 30 weight percent based on the totalvolume of the gaseous fuel mixture, and (c) a mercaptan compound in anamount less than 0.1 to 100 parts per million (volume/volume). The gascylinder has (a) a non-corrosive container comprising aluminum and (b) avalve that is connected to the non-corrosive container and that issuitable for use with a hydrogen-containing gas. The gaseous fuelmixture is positioned within the non-corrosive container of the gascylinder.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are described by way of example, withreference to the accompanying drawings, in which:

FIG. 1 shows a schematic drawing of an exemplary embodiment of arefillable and non-corrosive gas cylinder containing a gaseous fuelmixture.

DETAILED DESCRIPTION

An article is provided that can be used as a heating source whencombined with an oxygen-containing gas. Additionally, a heating methodis provided using the articles described herein. The article and methodcan overcome many of the environmental issues associated with currentportable heating sources and, in particular, those associated with theuse of acetylene gas. The article and method are particularly useful forvarious non-welding metallurgical applications.

In a first aspect an article is provided that include a gaseous fuelmixture and a refillable gas cylinder. The gaseous fuel mixturecomprises (a) hydrogen in an amount in a range of 30 to 95 volumepercent based on a total volume of the gaseous fuel mixture and (b)methane in an amount in a range of 5 to 70 weight percent based on thetotal volume of the gaseous fuel mixture. The gas cylinder has (a) anon-corrosive container and (b) a valve that is connected to thenon-corrosive container and that is suitable for use with ahydrogen-containing gas. The gaseous fuel mixture is positioned withinthe non-corrosive container of the gas cylinder.

FIG. 1 is a schematic drawing of one such article. The article includesa gas cylinder 10 that includes both the non-corrosive container 20 anda valve 30 that is connected to the non-corrosive container 20. Thegaseous fuel mixture 40 is positioned within the non-corrosive container20. The gaseous fuel mixture can be charged into the non-corrosivecontainer 20 of the gas cylinder 10 and discharged from the gas cylinder10 through the valve 30.

The gaseous fuel mixture, which can be used as a source of heat whencombined with an oxygen-containing gas, contains a mixture of hydrogenand methane. When used as a heating source, the gaseous fuel mixturecombusts in the presence of oxygen to produce carbon dioxide and water.There are few, if any, other combustion products. That is, the gaseousfuel mixture burns cleanly in the presence of oxygen. Both the gaseousfuel mixture and the combustion products are naturally present in theatmosphere and pose few, if any, environmental or health concerns.Stated differently, both the gaseous fuel mixture and its reactionproducts do not contaminate water, soil, or the atmosphere.

The gaseous fuel mixture typically contains 30 to 95 volume percenthydrogen and 5 to 70 volume percent methane based on a total volume ofthe gaseous fuel mixture. If a lower amount of methane is included inthe gaseous fuel mixture, a well formed flame can be difficult to obtainin the presence of oxygen. That is, the flame formed after mixing of thegaseous fuel mixture with an oxygen-containing gas can lift away fromthe tip of a torch. Such a flame is difficult to control or useeffectively in many applications. On the other hand, if a higher amountof methane is included in the gaseous fuel mixture, the cost of thegaseous fuel mixture tends to increase and the amount of carbon dioxideformed in the combustion products increases.

In some embodiments, the gaseous fuel mixture contains 40 to 95 weightpercent hydrogen and 5 to 60 weight percent methane or 45 to 95 weightpercent hydrogen and 5 to 55 weight percent methane. In some morespecific embodiments, it can be advantageous to have at least 50 weightpercent hydrogen in the gaseous fuel mixture. That it, some embodimentshave 50 to 95 weight percent hydrogen and 5 to 50 weight percentmethane, 60 to 95 volume percent hydrogen and 5 to 40 volume percentmethane, 65 to 95 volume percent hydrogen and 5 to 35 volume percentmethane, 70 to 95 volume percent hydrogen and 5 to 30 volume percentmethane, 75 to 95 volume percent hydrogen and 5 to 25 volume percentmethane, 80 to 95 volume percent hydrogen and 5 to 20 volume percentmethane, 85 to 95 volume percent hydrogen and 5 to 15 volume percentmethane, or 87 to 93 volume percent hydrogen and 7 to 13 volume percentmethane. Some particular gaseous fuel mixtures contain about 90 volumepercent hydrogen and 10 volume percent methane.

The hydrogen in the gaseous fuel mixture can be from any suitable sourceand can have any desired purity. Hydrogen is often a by-product producedwhen refining propane. The purity can be dependent on the particularapplication. The purity for hydrogen is often selected to be at least99.95 percent pure, at least 99.99 percent pure, at least 99.995 percentpure, or at least 99.999 percent pure. Standard industrial gradehydrogen, which usually has a purity of at least 99.95 percent, cancontain, for example, up to 10 parts per million (volume/volume) carbondioxide, up to 10 parts per million (volume/volume) carbon monoxide, upto 10 parts per million (volume/volume) oxygen, up to 400 parts permillion (volume/volume) nitrogen, and up to 34 parts per million(volume/volume) water. Hydrogen is commercially available in differentpurity levels from multiple suppliers.

The methane in the gaseous fuel mixture can be from any suitable sourceand can have any desired purity. Methane is a by-product of refiningpetroleum and can be found naturally. The purity for methane is oftenselected to be at least 99.0 percent pure, at least 99.9 percent pure,at least 99.97 percent pure, or at least 99.99 percent pure. Methanethat is at least 99.0 percent pure, which is often referred to as achemically pure grade, can contain impurities such as, for example, upto 150 parts per million (volume/volume) ethane, up to 5000 parts permillion (volume/volume), up to 150 parts per million (volume/volume)oxygen, up to 150 parts per million (volume/volume) other hydrocarbons,and up to 3 parts per million (volume/volume) water. Methane iscommercially available in different purity levels from multiplesuppliers.

The gaseous fuel mixture containing both hydrogen and methane typicallyhas less than 1000 parts per million (volume/volume) carbon monoxide andless than 1000 parts per million (volume/volume) carbon dioxide. Thepresence of either of these gases can result in the formation of acaustic environment when the gaseous fuel mixture is used as a heatingsource. Low levels of carbon monoxide are desired because of itstoxicity. In many embodiments, the concentration of both carbon monoxideand carbon dioxide in the gaseous fuel mixture is less than 500 partsper million (volume/volume), less than 200 parts per million(volume/volume), less than 100 parts per million (volume/volume), lessthan 50 parts per million (volume/volume), less than 20 parts permillion (volume/volume), or less than 10 parts per million(volume/volume).

A mercapto-containing compound may be added to the gaseous fuel mixtureto provide an odor sufficient to alert humans nearby of the presence ofthe gaseous fuel mixture. This can be helpful, for example, if a leakdevelops in the gas cylinder used to store the gaseous fuel mixture orif the valve of the gas cylinder is accidently opened or left opened.Any suitable mercapto-containing compound can be used. The strength ofthe odor of these compounds is typically related to their molecularweight. That is, mercapto-containing compounds of lower molecular weighttend to be more volatile. In some embodiments, the mercaptan-containingcompound is an alkyl mercaptan with the alkyl group having 1 to 10carbon atoms, 1 to 6 carbon atoms, 1 to 4 carbon atoms, 1 to 3 carbonatoms, or 1 to 2 carbon atoms. Some specific alkyl mercaptan compoundsinclude methyl mercaptan and ethyl mercaptan.

The human detection of many alkyl mercaptan compounds such as methylmercaptan can be less than 1 parts per million (volume/volume). Thus,only a small amount of the mercapto-containing compound such as an alkylmercaptan is needed in the gaseous fuel mixture to provide an alert. Thegaseous fuel mixture can contain up to 100 part per million(volume/volume) mercapto-containing compound based on the total volumeof the gaseous fuel mixture. For example, the mercapto-containingcompound can be present in an amount up to 80 parts per million(volume/volume), up to 75 parts per million (volume/volume), up to 50parts per million (volume/volume), up to 25 parts per million(volume/volume), up to 20 parts per million (volume/volume), or up to 10parts per million (volume/volume). In some examples, themercapto-containing compound is present in an amount in a range of 0.1to 100 parts per million (volume/volume), a range of 0.1 to 50 parts permillion (volume/volume), in a range of 0.1 to 25 parts per million(volume/volume), in a range of 0.1 to 20 parts per million(volume/volume), in a range of 1 to 20 parts per million(volume/volume), in a range of 0.1 to 10 parts per million(volume/volume), in a range of 1 to 10 parts per million(volume/volume), in a range of 0.1 to 5 parts per million(volume/volume), in a range of 1 to 5 parts per million (volume/volume),in a range of 0.1 to 2 parts per million (volume/volume), in a range of0.1 to 1 parts per million (volume/volume), in a range of 0.1 to 0.5parts per million (volume/volume), or in a range of 0.1 to 0.2 parts permillion (volume/volume).

The gaseous fuel mixture can be obtained from PRO-CYL LLC under thetrade designation HYDRO MIX.

The gaseous fuel mixture is typically free or essentially free ofvarious organic solvents such as, for example, acetone, dimethylformamide, N-methylpyrrolidinone, or mixtures thereof. These solventsare typically used with acetylene fuels but are not needed for thegaseous fuel mixtures described herein. When used in reference toacetylene or to organic solvents typically present when acetylene isused as a fuel gas, the term “essentially free” means less than 2 volumepercent, less 1 volume, less than 0.5 volume percent, less than 0.1volume percent (1000 parts per million), less than 0.05 volume percent(500 parts per million), less than 0.01 volume percent (100 parts permillion), less than 50 parts per million (volume/volume), or less that20 parts per million (volume/volume) based on a total weight of thegaseous fuel mixture. Depending on the purity of the methane used in thegaseous fuel mixture, there can be trace levels of other hydrocarbonspresent.

The contents within the non-corrosive container are typically free oressentially free of various solid filler materials such as variousstabilizers such a diatomaceous earth, cellulosic wood fiber, and thelike. No solid reactants are present in the gas cylinders for theproduction of the gaseous fuel mixture. As used herein in reference tofiller materials, the term “essentially free” means less than 2 percentby weight, less than 1 percent by weight, less than 0.5 percent byweight, less than 0.1 percent by weight, less than 0.05 percent byweight, or less than 0.001 percent by weight based on a total weight ofthe contents within the non-corrosive container. Stated differently, thestabilizers needed with other commonly used heating sources such asacetylene are not included in the current gaseous fuel mixtures andtypically are not present within the non-corrosive gas cylinder. This isparticularly advantageous because the amount of residual gas remainingin a spent gas cylinder can be less in the absence of the stabilizers.Additionally, the absence of the solid filler materials can lighten theweight of the article considerably. For example a gas cylinder having adiameter of about 6.9 inches (17.5 cm) and a length of about 33.1 inches(84.1 cm) that is filled with the gaseous fuel mixture described hereintypically weighs in a range of 15 to 20 pounds. A comparably sized gascylinder filled with acetylene weighs about twice this amount.

The gaseous fuel mixture is provided within a gas cylinder for use as aheating source. The gas cylinder is both refillable and non-corrosive.The gas cylinder includes both a non-corrosive container and a valvethat is connected to the non-corrosive container. The valve is suitablefor use with a hydrogen-containing gas and suitable for refilling. Thegaseous fuel mixture is placed within the non-corrosive container.

Although any suitable gas cylinder could be used, it is highly desirableto provide a heating source that is environmentally friendly. One aspectof being environmentally friendly is using gas cylinders that arerefillable. Many commonly available gas cylinders, particularly thoseavailable for use as portable heating sources (e.g., those weighing lessthan 10 pounds, less than 5 pounds, or less than 1 pound) such as thosecommonly used for propane and propylene, are not refillable. After use,the non-refillable gas cylinders are typically disposed of in a landfill or other disposal site. Refillable gas cylinders can beadvantageously used to reduce the amount of solid waste generatedthrough the use of the gaseous fuel mixture.

Another aspect of being environmentally friendly is using a gas cylinderthat is non-corrosive (i.e., not corrodible under typical useconditions). Many commonly used gas cylinders are constructed of metalssuch as carbon steel that can undergo corrosion. Corrosion may be causedfrom the outside of the gas cylinder, through contact with water, salts,carbon dioxide, and the like. Corrosion of the gas cylinders can be aproblem aesthetically. More importantly, however, when corrosion occurs,any residual fuel within the gas cylinders can leach into the soiland/or groundwater creating environmental concerns. Corroded gascylinders have been associated with explosions. That is, the residualgas in the gas cylinders can leak out of the gas cylinders and reactviolently upon exposure to air or upon exposure to other chemicals thatmay be present in the environment.

The amount of gas cylinder corrosion is typically controlled byproviding an outer coating to protect a corrodible metal (i.e., a metalthat can undergo corrosion under typical use conditions). That is, theouter coating reduces the likelihood of corrosion by minimizing exposureof the surface of the gas cylinder's corrodible portions to an oxidizingenvironment. This outer coating can be, for example, a layer of paint ora layer of a polymeric material. The outer coating is typically selectedto be tough or resistant to removal when scratched or bumped. Althoughthe outer coating can reduce corrosion, such coatings rarely totallyprevent corrosion because, over time, portions of the outer coating areremoved through use and the metal becomes exposed.

Thus, the gaseous fuel mixture described herein is provided within a gascylinder constructed out of non-corrosive materials (i.e., metals thatdo not undergo corrosion under typical use conditions although anoxidized layer may be present on the outer surface). Any metal or metalalloy can be selected that is non-corrosive and that can be fabricatedfor use as a gas cylinder. The non-corrosive container of the gascylinder can be fabricated, for example, from stainless steel, nickel ora nickel alloy, titanium or a titanium alloy, or aluminum or an aluminumalloy. In practice, however, aluminum or an aluminum alloy is typicallyselected based on cost considerations. In addition to be non-corrosive,gas cylinders fabricated from aluminum or an aluminum alloy tend to besignificantly lighter than comparably sized gas cylinders fabricatedfrom carbon steel. For example, gas cylinders of aluminum tend to be 40to 60 percent lighter than comparably sized gas cylinders of carbonsteel. Aluminum can be used to provide a gas cylinder that isnon-corrosive, lightweight, recyclable, strong, and economical.

The gaseous fuel mixture is typically introduced into the non-corrosive(i.e., non-corrodible) container of the gas cylinder through the valve.When used as a heating source, the gaseous fuel mixture is dischargedthrough the same valve and combined with oxygen. After discharging atleast a portion of the gaseous fuel mixture from the non-corrodiblecontainer, additional gaseous fuel mixture can be introduced into thenon-corrodible container through the valve.

The gas cylinder can have any desired size. Most of the gas cylindershave a length that is greater than the diameter. The diameter can be,for example, at least 7.6 cm (3 inches), at least 10.2 cm (4 inches), orat least 12.7 cm (5 inches) and can extend up to 25.4 cm (10 inches), upto 17.8 cm (7 inches), up to 22.9 cm (9 inches), or even more. Forexample, the diameter can be in a range of 7.6 to 25.4 cm (3 to 10inches), in a range of 7.6 to 20.3 cm (3 to 8 inches), or in a range of7.6 to 15.2 cm (3 to 6 inches). The length can be up to 152.4 cm (60inches) or even longer, up to 127 cm (50 inches), up to 101.6 cm (40inches), or up to 76.2 cm (30 inches). The length is often at least 20.3cm (8 inches), at least 25.4 cm (10 inches), at least 30.5 cm (12inches), or at least 38.1 cm (15 inches). For example, the length can bein a range of 20.3 to 152.4 cm (8 to 60 inches), in a range of 229.5 to140 cm (9 to 55 inches), in a range of 25.4 to 127 cm (10 to 50 inches),or in a range of 25.4 to 101.6 cm (10 to 40 inches). Some cylinders havea diameter of 7.6 cm (3 inches) to 15.2 cm (6 inches) such as, forexample, those referred to in the industry as MC cylinders and Bcylinders. Suitable gas cylinders such as those constructed of aluminumor an aluminum alloy can be obtained, for example, from CYL-TEC ofAurora, Ill.

In some embodiments, the gas cylinder filled with the gaseous fuelmixture is light enough to be carried by hand. In other embodiments, thecylinders must be transported using a cart and can be moved easily fromone location to another for use. In still other embodiments, one or moregas cylinders can be positioned at a first location and the gaseous fuelmixture is transferred to a second location of use through a system ofpipes or flexible tubing. For example, group of gas cylinders (e.g., 6gas cylinders or 12 gas cylinders) containing the gaseous fuel mixturecan be connected together through a manifold at a first location andthen transferred through a system of pipes or flexible tubing to thesecond location. As another example, a plurality of gas cylinderscontaining the gaseous fuel mixture can be stored on a trailer such as atruck trailer and the gaseous fuel mixture can be transferred from thetrailer to the use location through a system of pipes of flexible tubingto the second location.

The gas cylinder includes a valve that is suitable for use with ahydrogen-containing gas. This valve is often fitted with reverse threads(i.e., left-handed threads) and with a pressure-release feature. The gasfuel mixture is introduced and discharged through this valve. The valvefunctions as an on/off valve and as a course regulator of the flow rate.

The non-corrosive container of the gas cylinder can be filed with anysuitable amount of the gaseous fuel mixture. The initial pressure istypically selected based on the specifications for the particular gascylinder and depends on such factors as the cylinder size, thickness ofthe walls of the container, and the specific composition of the gaseousfuel mixture. The pressure of filling the gaseous fuel mixture dependsupon the capacity of the container. For example, the initial pressurecan be at least 10,340 kPa (1500 psi), at least 13,790 kPa (2000 psi),at least 15,278 kPa (2216 psi), at least 17,237 kPa (2500 psi), or atleast 20,684 kPa (3000 psi). If the gas cylinder is constructed ofaluminum or an aluminum alloy, the initial pressure is often close to15,278 kPa (2216 psi). Other than a mercapto-containing compound andtrace impurities that may be present in the hydrogen and the methane, noother compound or material is typically added to the gas cylindersbesides hydrogen and methane.

A gas flow regulator is typically added to the exit side of the valve(i.e., the side of the valve that is not directly connected to the gascylinder) and is used to better control the flow rate of the gaseousfuel mixture discharged from the gas cylinder. Suitable regulatorsinclude, for example, those commercially available under the tradedesignation CGA 350 from various suppliers.

A torch is often added on the exit side of the regulator (i.e., the sideof the regulator that is opposite the valve of the gas cylinder). Thatis, the regulator has a first end that is connected to the valve and asecond end that is connected to the torch. A flexible hose, such asthose commonly used in the welding industry, is typically used to jointhe torch to the regulator. The torch and, in particular, the torch tipare often selected based on the particular use of the gaseous fuelmixture as a heating source. The torch is usually configured to mix thegaseous fuel mixture with an oxygen-containing source (e.g., ambientair, compressed air, or compressed oxygen). Torches may includeadditional optional safety features such as check valves that allow flowin a single direction.

The oxygen combined with the gaseous fuel mixture to provide both aflame and heat can be a component of atmospheric air or can be providedas a compressed gas (e.g., air or oxygen) in another gas cylinder.Usually, the oxygen is supplied from another gas cylinder that isconnected to the torch through a regulator and a flexible hose such asthose commonly used in the welding industry. Torches connected tocompressed oxygen cylinders often provide a higher temperature flamethan those produced using atmospheric air as the oxidant. That is, ahigher temperature flame can result from the combustion of the gaseousfuel mixture with oxygen rather than air. Stated differently, theconcentration of oxygen mixed with the gaseous fuel mixture can be usedto regulate the temperature of the flame. The flame can be an oxidizingflame when the amount of oxygen exceeds the amount of the gaseous fuelmixture, can be a neutral flame when the amount of oxygen is roughlyequal to the amount of the gaseous fuel mixture, or can be a reducingflame when the amount of oxygen is less than the amount of the gaseousfuel mixture. The oxidizing flames tend to be of the highest temperature(e.g., about 3480° C. (6300° F.)). Neutral flames are often desirablefor cutting purposes; however, reducing flames can also be used forcutting such as thin materials where less distortion is desired.Reducing flames, which tend to be the coolest (e.g., about 3200° C.(5800° F.)), are often used for soldering.

Various tips can be used with the torches. The size and shape of the tipare typically selected based on the particular application. For example,for cutting metal, the tip size is usually selected based on thethickness of the metal being cut. Various tips are commerciallyavailable from a variety of suppliers such as, for example, PRO-CYL LLC.Torch tips that draw ambient air as the oxygen source are commonly usedin the heating and plumbing industry.

The gas cylinder may be equipped with additional safety features. Forexample, a polymeric sleeve can be positioned around at least a portionof the exterior of the gas cylinder such as around the non-corrosivecontainer. This polymeric sleeve can protect the gas cylinder frombecome scratched or scraped when positioned adjacent to other gascylinders.

The gas cylinder can be further equipped with a protective guard aroundthe valve that helps minimize the accidental opening of the valve orthat helps minimize the accidental dislodging or removal of the valve inthe event that the gas cylinder falls from its upright position. For gascylinders that are portable, the protective guard can be designed toprovide a handle or position for carrying the gas cylinder.

In another aspect, an article is provided that includes a gaseous fuelmixture and a refillable gas cylinder. The gaseous fuel mixturecomprises (a) hydrogen in an amount in a range of 70 to 95 volumepercent based on a total volume of the gaseous fuel mixture, (b) methanein an amount in a range of 5 to 30 weight percent based on the totalvolume of the gaseous fuel mixture, and (c) a mercaptan compound in anamount less than 0.1 to 100 parts per million (volume/volume). The gascylinder has (a) a non-corrosive container comprising aluminum and (b) avalve that is connected to the non-corrosive container and that issuitable for use with a hydrogen-containing gas. The gaseous fuelmixture is positioned within the non-corrosive container of the gascylinder.

The gas cylinders are often refillable, recyclable, lightweight (e.g.,lighter than steel or other commonly used gas cylinders), andnon-corrosive. The gaseous fuel mixture is environmentally friendly.

In yet another aspect, an environmentally friendly heating method isprovided. The method includes providing a refillable gas cylinder havinga non-corrosive container and a valve that is connected to thenon-corrosive container and that is suitable for use with ahydrogen-containing gas. The method further includes at least partiallyfilling the non-corrosive container of the gas cylinder with a gaseousfuel mixture that contains both hydrogen and methane. Hydrogen ispresent in the gaseous fuel mixture in an amount in a range of 30 to 95volume percent based on a total volume of the gaseous fuel mixture.Methane is present in the gaseous fuel mixture in an amount in a rangeof 5 to 70 volume percent based on the total volume of the gaseous fuelmixture. The method yet further includes supplying a heating source,wherein supplying includes discharging at least a portion of the gaseousfuel mixture from the non-corrosive container of the gas cylinderthrough the valve and combining the gaseous fuel mixture with anoxygen-containing gas. After discharging, the method still furtherincludes adding additional gaseous fuel mixture to the non-corrosivecontainer of the gas cylinder through the valve.

In this method, the gas cylinder is the same as described above.Additionally, the gaseous fuel gas mixture is the same as describedabove. The gas cylinder is designed such that it can be refilledmultiple times. That is, the gaseous fuel mixture initially introducedinto the gas cylinder can be used as a heating source upon beingdischarged from the gas cylinder and combined with an oxygen-containinggas. After discharging, additional gaseous fuel mixture can beintroduced into the gas cylinder to replace the gaseous fuel mixturethat was discharged. This newly introduced gaseous fuel mixture cansubsequently be used as a heating source. The charging (i.e.,introduction of gaseous fuel mixture into the gas cylinder) anddischarging (i.e., removal of gaseous fuel mixture from the gascylinder) steps may occur multiple times. For example, the charging anddischarging steps can occur at least 10 times, at least 20 times, atleast 50 times, or at least 100 times, so long as adequate safetytesting is performed on the gas cylinders and the gas cylinders continueto satisfy the appropriate safety standards.

The gaseous fuel mixture generates heat when mixed with anoxygen-containing gas and combusted. The combustion reaction generatesheat and allows the gaseous fuel mixture to function as a heat source.The heat source can be used to perform a variety of non-weldingmetallurgical tasks such as heating metal, cutting metal, brazing metal,soldering metal, flame spraying, and the like. The heat source also canbe used under appropriate conditions for cooking purposes (e.g., with astove or grill) or for providing heat to a space such as a room.

In one example, the combination of gaseous fuel mixture and oxygen isused as a heating source for cutting metal. This refers to severing themetal. Specialized cutting torch heads are typically used. Currently,cutting is often performed using acetylene. Acetylene cutting tends tobe dirty, and the cutting tip is especially susceptible to becomingclogged with debris. The gaseous fuel mixture described herein tends toburn cleaner than acetylene and is more desirable where contamination ofthe metal that is being cut needs to be minimized. In some cuttingapplications, the metal is steel or another ferrous-containing metal.

In other examples, the combination of gaseous fuel mixture and oxygen isused as a heating source for brazing metal or for soldering metal.Brazing and soldering both refer to metal joining processes. A fillermetal is usually heated above its melting point and then distributedbetween two or more close-fitting metal parts by capillary action. Thefiller metal is often flowed over one part (know as wetting) and thencooled to join the two parts together. The temperature associated withsoldering is lower than that associated with brazing. More specifically,the American Welding Society defines soldering as occurring attemperatures below 840° F. (450° C.) while brazing occurs at temperaturegreater than 840° F. (450° C.). That is, the filler metal used insoldering has a melting point less 840° F. (450° C.) than while thefiller metal used for brazing has a melting point greater than 840° F.(450° C.). Suitable filler materials for both soldering and brazing arecommercially available from multiple suppliers include, for example,PRO-CYL LLC and from UNITED BLAZING under the trade designationBRAZECRAFT and SOLDERCRAFT. A commonly used brazing filler material isknown as Low Fuming Bronze (LFB), which melts at about 880° C. (1620°F.). A commonly used soldering filler material is STAYBRITE 8. Withbrazing or soldering, the base metal being joined is heated but not to atemperature sufficient to cause melting (i.e., the base metals are notfused together). Steel, for example, melts at about 1150° C. (2100° F.).The color of the brazing filler material is often different than that ofthe metal parts joined together. The cohesion of the brazing material tothe metal parts joined together results in the joint formation.

In still other examples, the combination of gaseous fuel mixture andoxygen is used to heat metal such as pre-heating metal prior toperforming various tasks such as brazing, soldering, or cutting.Alternatively, the heating can be coupled with a controlled coolingprocess to prevent the formation of cracks in metals after beingsubjected to various high temperature processes.

In yet other examples, the combination of gaseous fuel mixture andoxygen is used as a heating source for flame spraying. Flame sprayingrefers to a method of coating a metal substrate. The coating material,which is often in the form of a wire or powder of metal or ceramicmaterial, is heated to its melting point and formed into droplets. Thedroplets are accelerated by high pressure air streams and sprayed ontothe surface of the metal substrate.

The gaseous fuel mixture combined with an oxygen-containing gas istypically not a suitable heat source for welding. Unlike the flameproduced by the combination of oxygen and acetylene, the flame resultingfrom the combination of oxygen and the gaseous fuel mixture describedherein tends to be fairly uniform in temperature. There is no inner coneregion that is as hot as that present in an acetylene flame (i.e., inthe blue inner cone region of the acetylene flame). There is nolocalized region as in the acetylene flame that is hot enough to meltmetals such as steel. When used for welding purposes, the joints formedtend to be weak compared to those formed with an acetylene flame.

Even though the flame produced by combustion of the gaseous fuel mixtureis not suitable for welding, it is particularly well suitable for manynon-welding applications involving the joining of metal parts or thetreatment of metal surfaces. The flame produced by the combustion of thegaseous fuel mixture is particularly well suited for non-weldingapplications such as cutting, brazing, and soldering because of itslower temperature compared to acetylene and because of its cleanernature than acetylene. The flame tends to be quite uniform intemperature throughout and this uniformity is useful when used inapplications where excessive heat can cause damage to the metal beingjoined.

After the gaseous fuel mixture has been discharged (e.g., partiallydischarged or completely discharged) from the gas cylinder, thedischarged gas cylinder can be returned to the vendor or to a refillingstation. The vender or the refilling station can then recharge (i.e.,refill) the gas cylinder with additional gaseous fuel mixture. Incertain embodiments, the exterior of the gas cylinder may includeinformation about the location of these refilling stations or caninclude a website address with such information. In some instances, thevendor, the refilling station, or both obtains a license from themanufacturer to recharge the gas cylinder with the gaseous fuel mixture.

The refillable nature of the currently described heating sources offerseveral environmental and safety advantages over commonly used heatingsources. For example, using refillable gas cylinders can diminish thenumber of gas cylinders that end up as solid waste. The non-corrosivenature of the gas cylinders lowers the risk of contamination if residualgaseous fuel mixture remains in gas cylinders or if gas cylinders aredisposed of (perhaps accidentally) in an improper manner. When theuseful lifetime of the gas cylinder is reached, it can usually berecycled, particularly if it is made of aluminum. This also can lead toreduced solid waste compared to many currently used gaseous heatingsources.

The gaseous fuel mixture can be combusted to provide a flame withminimal soot or that is free of soot. A torch containing a mixture ofoxygen and the gaseous fuel mixture is typically easy to light. Nospecial torches are needed. That is, industrial standard torches andtorch tips can be used without modification.

Additionally, the flame noise is relatively low because of therelatively low flow rates (i.e., the relatively low pressure settings onthe regulator) of the gaseous fuel mixtures that are needed to sustain aflame. Lower flow rates tend to correlate with lower noise levels (i.e.,lower decibels). For example, to cut a steel plate having a thickness of2.54 cm (1 inch), a fuel pressure of 34.5 to 68.9 kPa (5 to 10 psi) canbe used in combination with an oxygen pressure of 275.6 to 344.5 kPa (40to 50 psi) to cut at a speed of 35.5 to 50.8 cm per minute (14 to 20inches per minute). In another example, to cut a steel plate having athickness of 25.4 cm (10 inches), a fuel pressure of 68.9 to 103.4 kPa(10 to 15 psi) can be used in combination with an oxygen pressure of413.4 to 482.3 kPa (60 to 70 psi) to cut at a speed of 10.2 to 15.2 cmper minute (4 to 6 inches per minute).

Various items are provided that are articles or method of heating.

Item 1 is an article is provided that includes a gaseous fuel mixtureand a refillable gas cylinder. The gaseous fuel mixture comprises (a)hydrogen in an amount in a range of 30 to 95 volume percent based on atotal volume of the gaseous fuel mixture and (b) methane in an amount ina range of 5 to 70 weight percent based on the total volume of thegaseous fuel mixture. The gas cylinder has (a) a non-corrosive containerand (b) a valve that is connected to the non-corrosive container andthat is suitable for use with a hydrogen-containing gas. The gaseousfuel mixture is positioned within the non-corrosive container of the gascylinder.

Item 2 is the article of item 1, wherein the gaseous fuel mixturecomprises 75 to 95 volume percent hydrogen and 5 to 25 volume percentmethane.

Item 3 is the article of item 1 or 2, wherein the gaseous fuel mixturecomprises 85 to 95 volume percent hydrogen and 5 to 15 volume percentmethane.

Item 4 is the article of any one of items 1 to 3, wherein the gaseousfuel mixture further comprises a mercapto-containing compound.

Item 5 is the article of item 4, wherein the mercapto-containingcompound is methyl mercaptan.

Item 6 is the article of any one of items 1 to 5, wherein thenon-corrosive container comprises aluminum or an aluminum alloy.

Item 7 is the article of any of one of items 1 to 6, wherein the gascylinder further comprises polymeric sleeve arranged on a portion ofcontainer.

Item 8 is the article of any one of items 1 to 7, wherein the fuelmixture is free or essentially free of acetylene, acetone, dimethylformamide, N-methylpyrrolidinone, or mixtures thereof.

Item 9 is the article of any one of items 1 to 8, wherein the fuelmixture is free or essentially free of a solid filler material.

Item 10 is the article of any one of items 1 to 9, further comprising aprotective guard surrounding the valve, wherein the protective guard isconfigured for use as a handle for carrying the gas cylinder.

Item 11 is the article of any one of items 1 to 10, wherein the valve issuitable for discharging the fuel mixture and for refilling the gascylinder with additional fuel mixture after discharging.

Item 12 is the article of any one of items 1 to 11, further comprising agas regulator and a torch suitable for cutting metal, brazing metal, orsoldering metal, wherein the regulator has a first end connected to thevalve and a second end connected to the torch.

Item 13 is the article of item 12, further comprising a gas cylindercontaining an oxygen-containing gas connected to the torch.

Item 14 is a method of heating that can be environmentally friendly. Themethod includes providing a refillable gas cylinder having anon-corrosive container and a valve that is connected to thenon-corrosive container and that is suitable for use with ahydrogen-containing gas. The method further includes at least partiallyfilling the non-corrosive container of the gas cylinder with a gaseousfuel mixture that contains both hydrogen and methane. Hydrogen ispresent in the gaseous fuel mixture in an amount in a range of 30 to 95volume percent based on a total volume of the gaseous fuel mixture.Methane is present in the gaseous fuel mixture in an amount in a rangeof 5 to 70 volume percent based on the total volume of the gaseous fuelmixture. The method still further includes supplying a heating source,wherein supplying includes discharging at least a portion of the gaseousfuel mixture from the non-corrosive container through the valve andcombining the gaseous fuel mixture with an oxygen-containing gas. Afterdischarging, the method yet further includes adding additional gaseousfuel mixture to the non-corrosive container through the valve.

Item 15 is the method of item 14, further comprising using the heatingsource to heat metal for a non-welding application.

Item 16 is the method of item 15, wherein the non-welding application iscutting, brazing, soldering, flame spraying, or a combination thereof.

Item 17 is an article is provided that includes a gaseous fuel mixtureand a refillable gas cylinder. The gaseous fuel mixture comprises (a)hydrogen in an amount in a range of 70 to 95 volume percent based on atotal volume of the gaseous fuel mixture, (b) methane in an amount in arange of 5 to 30 weight percent based on the total volume of the gaseousfuel mixture, and (c) a mercaptan compound in an amount less than 0.1 to100 parts per million (volume/volume). The gas cylinder has (a) anon-corrosive container comprising aluminum and (b) a valve that isconnected to the non-corrosive container and that is suitable for usewith a hydrogen-containing gas. The gaseous fuel mixture is positionedwithin the non-corrosive container of the gas cylinder.

Item 18 is an article of item 17, wherein the gaseous fuel mixturecomprises 85 to 95 volume percent hydrogen and 5 to 15 volume percentmethane.

Item 19 is an article of item 17 or 18, further comprising a gasregulator and a torch suitable for cutting metal, brazing metal, orsoldering metal, wherein the regulator has a first end connected to thevalve and a second end connected to the torch.

Item 20 is the article of item 19, further comprising a gas cylindercontaining an oxygen-containing gas connected to the torch.

Item 21 is the article of any one of items 17 to 20, wherein the gascylinder is recyclable, and lightweight and wherein the gaseous fuelmixture is environmentally friendly.

Item 22 is a method of using the article of any one of items 1 to 13 oritems 17 to 21 for heating metal, brazing metal, or a combinationthereof.

Item 23 is the method of item 22 wherein the heating metal, brazingmetal, or a combination thereof is performed on component of a heating,ventilation, or air conditioning system.

Item 24 is the article of any one of items 1 to 13 or items 17 to 21,wherein the gas cylinder has a diameter of 7.6 cm (3 inches) to 15.2 cm(6 inches).

EXAMPLES Example 1 Cutting

A gaseous fuel mixture containing 90 volume percent hydrogen and 10volume percent methane was used in combination with oxygen for cutting.The oxygen was dispensed at a rate of 30 cubic feet per hour and thegaseous fuel mixture was dispensed at a rate of 2 cubic feet per hour.The torch had a SMITH #1 tip. A sample of 0.5 inch thick A-36 mild steelplate was cut at a rate of 24 inches per minute using the torch.

The gaseous fuel mixture burned cleanly (i.e. without creating soot andcarbon buildup), and exhibited a smooth transitional shutdown withoutpopping or flashback.

Example 2 Brazing

A gaseous fuel mixture containing 90 volume percent hydrogen and 10volume percent methane was used in combination with oxygen for brazing.The oxygen was dispensed at a rate of 30 cubic feet per hour and thegaseous fuel mixture was dispensed at a rate of 2 to 3 cubic feet perhour. The torch had a SMITH MW205 braze tip.

Two steel coupons (low carbon content, SAE 1018 steel) were joined bybrazing. The brazing rod was a Low Fuming Brazing (LFB) rod. The steelcoupons were heated to a cherry red color. The brazing rod was melted tojoin the two steel coupons together. That is, the molten blazing rodmaterial flowed over the two coupons and joined them together bymolecular surface cohesion. The color of the brazing was different thanthe color of the steel coupons.

The gaseous fuel mixture burned cleanly (i.e. without creating soot andcarbon buildup), and exhibited a smooth transitional shutdown withoutpopping or flashback.

Comparative Example 1 Welding with Gaseous Fuel Mixture

A gaseous fuel mixture containing 90 volume percent hydrogen and 10volume percent methane was used in combination with oxygen for welding.Both gases, the gaseous fuel mixture and compressed oxygen, weredispensed at a rate of 20 cubic feet per hour to provide a neutralflame. A standard welding tip (SMITH torch with a standard 205 mixertip) was used.

A 70 S2 wire was used as the welding rod or filling material. 70 S2 wireis commonly used for welding and contains a copper coating around acarbon steel core. The copper coating acts as a protective barrieragainst oxidization from ambient environment such as air and also actsas an agent that promotes better flow of material, or “puddling”. Themelting point and the tensile strength of the welding rod are comparableto that of the two steel coupons described below.

Two steel coupons (low carbon content, SAE 1018 steel) were placed sideby side, with one edge of each coupon in contact with the other coupon.The 70 S2 wire melted slowly but did not flow in a satisfactory mannerbecause of the relatively low flame temperature. That is, there nopuddles of the molten material formed. The temperature was insufficientto create a bead of the 70 S2 wire on the surface of the steel coupons.After welding, the coupons fell apart when the joined part was bentslightly due to the low weld or joint strength. Stated differently,there was a lack of fusion of the two coupons together and a lack ofpenetration. Further, high levels of sparking suggested that there maybe hydrogen embrittlement.

Comparative Example 2 Welding with Acetylene

The gaseous fuel mixture of Comparative Example 1 was replaced withacetylene. The oxygen/acetylene flame was neutral. Two steel couponswere welded in the same manner as described in Comparative Example 1.The 70 S2 wire melted and flowed sufficiently well to form puddles ofthe molten material. A strong weld resulted. When the joined couponswere bent such that the ends of the coupons opposite the weld touchedeach other, the weld did not break.

What is claimed is:
 1. A method for heating, the method comprising A)providing a refillable gas cylinder comprising a non-corrosive containerand a value that is connected to the non-corrosive container and that issuitable for use with a hydrogen-containing gas; wherein the refillablegas cylinder contains a gaseous fuel mixture comprising: (a) hydrogen inan amount in a range of 30 to 95 volume percent based on a total volumeof the gaseous fuel mixture; and (b) methane in an amount in a range of5 to 70 volume percent based on a total volume of the gaseous fuelmixture; and B) supplying a heating source, wherein supplying comprisesdischarging at least a portion of the gaseous fuel mixture from thenon-corrosive container through the valve and combining the gaseous fuelmixture with an oxygen containing gas; wherein the gaseous fuel mixtureburns without creating soot or carbon buildup.
 2. The method of claim 1,wherein the gaseous fuel mixture comprises 75 to 95 volume percenthydrogen and 5 to 25 volume percent methane.
 3. The method of claim 1,wherein the gaseous fuel mixture comprises 85 to 95 volume percenthydrogen and 5 to 15 volume percent methane.
 4. The method of claim 1,wherein the gaseous fuel mixture further comprises a mercapto-containingcompound.
 5. The method of claim 4, wherein the mercapto-containingcompound is methyl mercaptan.
 6. The method of claim 1, wherein thenon-corrosive container comprises aluminum or an aluminum alloy.
 7. Themethod of claim 1, wherein the gaseous fuel mixture is free oressentially free of acetylene, acetone, dimethyl formamide,N-methylpyrrolidinone, or mixtures thereof.
 8. The method of claim 1,wherein the gaseous fuel mixture is free or essentially free of a solidfiller material.
 9. The method of claim 1, wherein the valve is suitablefor discharging the fuel mixture and for refilling the gas cylinder withadditional fuel mixture after discharging.
 10. The method of claim 1,wherein the heating does not include welding metallurgical applications.11. The method of claim 1, wherein the heating is selected from one ormore of the group consisting of: heating metal, cutting metal, brazingmetal, soldering metal, flame spraying, cooking, and providing heat to aspace.
 12. The method of claim 1, wherein the gas cylinder furthercomprises a gas regulator and a torch suitable for cutting metal,brazing metal, or soldering metal, wherein the regulator has a first endconnected to the valve and a second end connected to the torch.
 13. Themethod of claim 12, wherein the oxygen containing gas is contained in aseparate gas cylinder and is connected to the torch.
 14. The method ofclaim 1, wherein the gaseous fuel mixture comprises less than 500 partsper million carbon monoxide.
 15. The method of claim 1, wherein at least99.3 volume percent of the gaseous fuel mixture is hydrogen and methane.16. A method for cooking, the method comprising A) providing arefillable gas cylinder comprising a non-corrosive container and a valuethat is connected to the non-corrosive container and that is suitablefor use with a hydrogen-containing gas; wherein the refillable gascylinder contains a gaseous fuel mixture comprising: (a) hydrogen in anamount in a range of 30 to 95 volume percent based on a total volume ofthe gaseous fuel mixture; and (b) methane in an amount in a range of 5to 70 volume percent based on a total volume of the gaseous fuelmixture; and B) supplying a heating source, wherein supplying comprisesdischarging at least a portion of the gaseous fuel mixture from thenon-corrosive container through the valve and combining the gaseous fuelmixture with an oxygen containing gas.
 17. The method of claim 16,wherein the cooking is performed on a grill.
 18. The method of claim 16,wherein the gaseous fuel mixture comprises 75 to 95 volume percenthydrogen and 5 to 25 volume percent methane.
 19. The method of claim 16,wherein the gaseous fuel mixture comprises 85 to 95 volume percenthydrogen and 5 to 15 volume percent methane.
 20. The method of claim 16,wherein at least 99.3 volume percent of the gaseous fuel mixture ishydrogen and methane.